In the case of driving an object to be driven by using an actuator, it is important to learn a positional relationship between the actuator and the object to be driven, for the purpose of performing high-accuracy drive control. For example, in a reference opening position learning device according to Patent Literature 1, an intake air swirl control valve is driven to move to a reference position by an actuator at the time when an engine stops, and the reference position is learned from the degree of opening of the intake air swirl control valve which is detected by a position sensor.
However, as disclosed in above-mentioned Patent Literature 1, only the implementation of position learning at the time when the engine stops leads to a problem that a mechanism element gets warm and becomes deformed due to thermal expansion, and the reference position is shifted. Thus, a control valve opening and closing control device according to Patent Literature 2 learns a reference position from the degree of opening of an intake air swirl control valve which is detected by a position sensor when the intake air swirl control valve is driven to move to the reference position during operation of the engine.